Nuclear pore

The nucleus of an eukaryotic organism is an organelle surrounded by a nuclear envelope, which contains nuclear pores. The pores allow the transportation of material between the nucleus and the cytoplasm through nucleocytoplasmic transport.  The nuclear pore is composed of multiple proteins, allowing the entry of small water soluble molecules and proteins of a small molecular weight from the cytoplasm into the nucleus. The nuclear pores further allow instructions from the nucleus to enter the cytoplasm in the form of ribonucleo protein complexes.